The invention generally relates to the field of imaging systems, and specifically relates to systems and methods for registering plates such as lithographic or flexographic plates in a platemaking system.
In many pre-press imaging systems, such as imagesetters or platesetters, a plurality of sheets or plates (hereafter referred to as plates) of recording media are separately exposed by an imaging source. Each plate may provide a pattern for a different color (e.g., yellow, magenta, cyan and possibly black), and these plates must be registered with one another during printing of the final multi-color image. The recording media to be imaged by a pre-press imaging system is commonly supplied in web form or in discrete plates. The recording media may include photosensitive material, radiation sensitive material, thermally sensitive material, or any other type of imageable material.
Registration of the plates is typically performed by punching or creating notches or holes or other features that may be used to register plates (hereafter referred to as registration features) in the recording media at specific registration locations. These registration features must be accurately and consistently applied to the plates, and the features are typically applied either while the recording media is in contact with a media support surface during imaging, or after imaging at a separate punch press station.
During imaging, a movable optical carriage is typically used to displace a laser system or other imaging source in a slow scan direction along a stationary or moving, curved or planar, media support surface (e.g., an external drum, and internal drum, a flatbed, or other support surface). The imaging source exposes a supply of recording media supported on, and held against, the media support surface. Generally, the imaging source includes an optical system for scanning one or more lasers or other radiation beams, each modulated by a digital information signal, over the recording media to record an image onto the recording media. Generally, the information signal is recorded onto a supply of recording media mounted about the external drum by displacing the imaging source relative to the media support surface, e.g., an external drum. This may be accomplished in a number of ways, including rotation of the external drum in combination with a lateral translation of the imaging source, etc. In certain systems, the external drum is rotated while the imaging source is displaced in discrete steps or continuously along the length of the external drum to record data onto the recording media.
Although the media may be accurately positioned when being imaged and punched while the media is on the media support surface, the presence of the punch apparatus in the imaging area may present mechanical difficulties. For example, plates may bind or become misaligned during loading into the image area as they pass through a punch opening, particularly if the leading edge of the plate is curled for any reason. Although increasing the size of the punch opening may alleviate the problem, this may increase the risk of mechanical error if the punch assembly requires too much mechanical movement. It is generally desirable to minimize the amount of mechanical movement of a punch assembly.
The use of a separate punch press station, on the other hand, requires additional floor space as well as separate processing steps, which increase the risk of occurrence of human and other errors. Moreover, plates are typically punched after chemical processing of the plates since they must be handled during transport to the punch press station.
There is a need, therefore, for an improved system and method for registering plates in a pre-press imaging system.
The invention provides an imaging system for imaging and registering recordable media. The imaging system includes an input opening through which recordable media may be input to the imaging system, an imaging unit, a registration unit and an output opening through which registered imaged media may exit the imaging system. The imaging unit is for imaging the recordable media that is received through the input opening, and provides imaged media. The registration unit is for receiving imaged media from the imaging unit, and for registering the imaged media by creating registration features in the imaged media. The registration unit provides registered imaged media.